Apparatus for minimizing waste in treating a web

ABSTRACT

The invention provides apparatus for cutting or printing a series of closely spaced areas along a web of material where the length of each area is less than the periphery of the forme carrying roll which produces the cut or printed area and where the roll runs continuously at high speed, and avoids the areas becoming spaced by a distance equal to the peripheral dimension minus the area length, by arresting the web and returning it between each two successive cutting or printing operations. The web is accelerated forwardly to a speed matched to that of the roll at the point when printing or cutting commences and decelerated and reversed subsequent to cutting or printing ceasing.

[451 Sept. 4, 1973 l l APPARATUS FOR MINIMIZING WASTE IN TREATING A WEB [75] Inventor: Thomas Desmond Bishop, Knowle,

Solihull, Warwickshire, England [73] Assignee: The Deritend Engineering Company Limited, Birmingham, England [22] Filed: Mar. 15, 1971 [21] App]. No.: 124,414

12/1971 Rubenstein 101/228 X 8/1956 Tison lOl/228 Primary Examiner-Robert E. Pullfrey Assistant Examiner--Clifford D. Crowder Att0rney-Marshall & Yeating [57] ABSTRACT The invention provides apparatus for cutting or print ing a series of closely spaced areas along a web of material where the length of each area is less than the periphery of the forme carrying roll which produces the cut or printed area and where the roll runs continuously at high speed, and avoids the areas becoming spaced by a distance equal to the peripheral dimension minus the area length, by arresting the web and returning it between each two successive cutting or printing operations. The web is accelerated forwardly to a speed matched to that of the roll at the point when printing or cutting commences and decelerated and reversed subsequent to cutting or printing ceasing.

2 Claims, 10 Drawing Figures BACKGROUND OF THE INVENTION This invention relates to feeders for web material for use with printing and more particularly die-cutting apparatus of the kind which comprises a pair of rolls of which one (called the impression roll) carries a stereo, forme or like. When the forme, for example, extends over the whole of the periphery of the impression roll the web may be fed continuously through the nip between the rolls at the same speed as the peripheries of the rolls and a series of printed and/or cut blanks produced along the length of the web, and the small amount of waste between successive blanks formed in or from the web will be equal in length to the space between the leading and trailing edges of the forme or the like measured about the periphery of the roll.

Apparatus of this kind is required to produce blanks varying in size from small to large, and the largest which may be produced is equal to, or very slightly less than, the dimension of the periphery of the roll. With all smaller blanks, the length of web between each two blanks is waste and the amount of waste which is produced may be unacceptable. For this reason it has been the more usual practice hitherto to produce such blanks from discrete pieces of material i.e., to cut the web into blanks and feed the same individually through the apparatus, instead of feeding the web material through the apparatus, thus introducing an additional machine and an extra handling step.

SUMMARY OF THE INVENTION The object of the present invention is to provide means whereby web continuous material may be used with a minimum amount of waste, even when used to produce blanks of a length substantially smaller than the peripheral dimension of the operating roll.

In accordance with the invention considered broadly, apparatus of the kind referred to is provided with means for feeding web a through the roll nip, and means for interrupting the feed of the web in timed relation to the impression roll thereof.

In one arrangement, the forme, stereo or the like projects above the normal surface of the impression roll, so that when a portion of the forme or stereo is present in the nip between the two rolls, the web material in the nip is fed thereby, but when the trailing end of the forme or stereo has passed the nip and the leading end of the same has not reached the nip, there is a clearance at the nip so that the web is not driven by the nip and the web is positively accelerated by feed rolls up to a matched speed with the impression roll at the time when the leading edge of the stereo or forme approaches the nip, and after the trailing end of the forme or stereo has left the nip, the web is decelerated, stopped; and reversed, so as to draw the web back through the nip-first to a position in which the trailing edge of the blank produced by the operating roll registers with the nip, and then beyond that. The web is then stopped,'and subsequently at the start of the next operation restarted again in the forward direction so as to accelerate it up to the matched speed so that the trailing end of the blank on the web is again at the nip, or possibly slightly beyond the nip when the leading end of the forme or stereo re-enters the nip.

By these means the waste between twosuccessive blanks on the web may be minimised very substantially.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic elevation showing a pair of rolls operating upon a web; a

FIG. 2 is a plan view of the same showing a series of blanks formed by the operating roll, and the waste between those blanks;

FIGS. 1 and 2 relate to known arrangements.

FIG. '3 is a graphical illustration relating to FIGS. 4-10;

FIG. 4 is a diagrammatic elevation of a preferred apparatus according to the invention;

FIGS. 5 to 10 inclusive show six successive stages in a cycle of use of the apparatus illustrated in FIG. 4, and

Referring now to FIG. 1, this shows the impression roll 20 and the complementary roll 21 with the web material 22 extending through the nip between the two rolls. The forme 23 is illustrated as extending over slightly more than 180 of the periphery of roll 20, and when the forme is located in the nip between the rolls, it drives the web material 22 so as to feed the latter whilst the treatment step, for example die-cutting of the web, takes place.

FIG. 2 shows a series of blanks 25 being cut out of the web 22, and illustrates the waste W between each two successive blanks.

Referring now to FIG. 4 showing a preferred apparatus, impression roll 20 carries, fast therewith, but adjustably mounted thereon, a double cam 35, 36 of which the respective parts are adjustable circumferentially for a purpose to be described. Roller 20 is chain connected to shaft 40 carrying a cam 41.

A pair of feed rolls 43, are provided, the roll 43 having a pinion at one end which is meshed with an arcuate rack 47 carried by a bellcrank lever 49 which is pivoted on a fixed axis 50 and is urged by spring 51. The bellcrank lever carries a roller 53 which acts as a cam follower in respect of the cams 35 and 36.

Cam 41 acts on a roller carried by a bellcrank lever 61 which is pivoted at 62 and connected by a link 64 to a crank 65 which turns a shaft 67 on which a further crank 69 is located, roll 45 being carried by crank 69.

During rotation of the operating roll 20 the earns 35 and 36 will displace the follower 53 and swing the bellcrank lever 49 about its pivot 50 so as to displace the rack 47 past the feed roll 43 and hence rotate the feed roll. The direction of rotation and the rate of acceleration depend upon the cam shape.

The operation of cam 41 is to lift and lower roller 45 in timed relation to the operating roll 20.

Reference is now made to FIG. 3 illustrating one complete operating cycle of the apparatus of FIG. 4. It is desired to accelerate the web from rest to a speed matched to that of the roll 20 periphery, and to allow the web to be fed through the roll pair 20, 21 by the forme or stereo co-operating with the blank and the complementary roll 21, and then after the printing or cutting operation has been completed, decelerate the blank to rest, accelerate the blank in the opposite direction so as to return it through the roll nip whilst the forme or stereo is in an inoperative position relative to the web and nip, and again bring the web to rest, in such a position that when the next cycle starts and the web is again accelerated, it will reach maximum speed (that of the periphery of roll 20) when the trailing edge of the previously cut blank or the like of the web has reached or slightly passed the nip position, and when the leading edge of the forme or stereo reaches the nip position. Hence the next successive blank can be formed or produced almost immediately behind the first blank on the web, and so on.

For convenience it is assumed that the rate of acceleration of the web at any time is uniform, irrespective of the direction. This rate will depend upon the surface of the board, the nature of the feed roll, and other factors which set a maximum limit upon acceleration which is possible without slip. By using a uniform rate of acceleration whether in a positive or negative sense, the portions of the cycle devoted to acceleration of the web from rest to maximum speed in the forward direction and similarly to acceleration in the negative sense to maximum speed in the reverse direction, are equal. Another factor contributing to the length of each accelerating and decelerating portion of the cycle, is the effective length of the rack 47. In order to keep this at a minimum, it is preferred to utilise otherwise idle (so far as the rack is concerned) portions of the cycle for returning the rack so that it may make a repeat stroke in the same direction to like effect, rather than making an excessively long single stroke in one direction.

In FIG. 3 the line 70 to 77 represents the peripheral speed of the feed roll 43 and also the sense or direction of the rotation. The horizontal line marked to 360 at respective ends,.represents one complete cycle or revolution of the roll 20. During that revolution, the web is accelerated in a forward direction from the horizontal line (representing zero speed) to a speed represented by the chain dot line 80 which is the peripheral speed of roll 20. At the end of this acceleration, that is at the end of line 70 in FIG. 1 l, the web is travelling at the peripheral speed of roll 20, and die-cutting (or any other treatment operation) can commence. During this acceleration period, roll 45 is in a lowered position, so as to co-operate with the feed roll 43, and enable the web to be accelerated between the two. At the end of this period, roll 45 is lifted so that the web may continue to travel during the die-cutting or like operation, irrespective of feed roll 43, and the web may be displaced slightly into contact with roll 43 by roll 45, and released therefrom when the roll 45 is elevated.

Consequently it is possible for the feed roll 43 to be decelerated down to zero speed represented by line 71, and during the whole of the portions of the cycle represented by lines 70 and 71, the bellcrank 49 has been moving in one direction about its pivot 50 and the roll 43 has been accelerated and decelerated by movement of the rack 47 in a single direction.

The bellcrank is then reversed to return the rack to the same position as it was at the start of the initial acceleration period represented by line 70. Lines 74 to 77 represent a repeat operation on the part of the bellcrank, with the forward acceleration of the roll terminating when it is at the same peripheral speed as roll and in the same direction as roll 20 and at the time when the die-cutting or like operation is completed. As indicated on FIG. 3, the roll 45 is then lowered into contact with the web so as to press the same into contact with the feed roll 43 to permit subsequent decelerationof the web to zero speed, as represented by line 75, acceleration of the web to the same speed but in the reverse direction as indicated by line 76, and again deceleration of the web to zero with continued reverse feed of the web as indicated by line 77.

It will be noted that the complete cycle thus includes the accelerating and decelerating times plus two intervals shown on FIG. 3 as y and z. Interval z is necessary so that after the completion of the movement indicated by line 73, which restores the quadrant to starting position, the roll will not be accelerated until an appropriate point in the cycle; hence 2 will be of variable length and will be a minimum or zero when the die cutting or like operation is carried on over a time equal to that taken for the operations indicated by lines 71 to 74 inclusive on FIG. 3, i.e., when the forme or stereo extends over an arcuate portion of the roll 20 periphery of equal proportion of the whole periphery as the times for the operations indicated by lines 71 to 74 are of the time taken for one complete cycle. In such event, i.e., when 2 equals zero, then y is a maximum. Equally, when a larger blank is to be produced, so that 2 increases in magnitude, y decreases and in the extreme case y equals zero. These two factors are adjusted by moving the cam part 35 relative to cam part 36, and the intervals between them correspond to y and 2..

Where the forme or stereo extends over a particularly small arc of the periphery of the operating roll 20, then it may be duplicated, and so on. Hence in practice it is only necessary to provide for the case where the forme or stereo extends over a little more than 180 of the periphery and as long as y plus 2 plus the aggregate of 77 equals 360 then waste may be kept to substantially zero.

Turning now to FIG. 5 of the drawings, this shows the operative arrangement of the parts when the leading edge 32 approaches the nip, the roll 45 is lowered, and roll 43 is accelerating the web forwardly so that the trailing edge of the last produced or formed blank will reach the nip or preferably just pass the nip as the leading edge 32 approaches the nip.

FIG. 6 shows the roll 43 decelerating and the roll 45 lifted so as to allow the web to be fed through the nip by the forme.

FIG. 7 shows the rack being returned.

FIG. 8 shows the feed roll 43 being accelerated forwardly again, and the roll 45 being lowered as the trailing end 31 of the forme or stereo passes the nip.

FIG. 9 shows the feed roll decelerating to zero and retarding the web, prior to acceleration of the web in the reverse direction shown in FIG. 10.

In practice, it may be desirable for the feed roll to be held at maximum forward speed momentarily, whilst the pressure roll 45 is lowered, so as to allow that roll to be accelerated by the web, prior to termination of the cut effected by the forme and to avoid snatch. Similarly, the feed roll may be held at its maximum speed with the roller 45 engaged, a little before the commencement of the cutting operation and before the deceleration period starts for similar reasons.

I claim:

1. Apparatus for minimizing the untreated portions of a web while producing a series of treated areas along the length of a web, comprising a pair of treatment rolls carrying treatment means which grip the web only while effecting treatment, a pair of feed rollers between which the web passes, apparatus for producing relative movement of the feed rollers, which operates in synchronism with the treatment means to cause the rollers to release the web as it is engaged by the treatment anism for controllably oscillating the feed roller comprises a pivoted sector carrying an arcuate rack for driving one of the feed rollers, and a pair of angularly adjustable cams driven in synchronism with one of the treatment rolls, for actuating the sector to drive such feed roller forward and baclc once as the treatment means takes over the gripping of the web and again as such roller takes over the gripping of the web.

i i I. i 

1. Apparatus for minimizing the untreated portions of a web while producing a series of treated areas along the length of a web, comprising a pair of treatment rolls carrying treatment means which grip the web only while effecting treatment, a pair of feed rollers between which the web passes, apparatus for producing relative movement of the feed rollers, which operates in synchronism with the treatment means to cause the rollers to release the web as it is engaged by the treatment means and to engage the web as it is released by the treatment means, and mechanism for controllably oscillating at least one of the feed rollers, with each operation of the treatment means, through two complete cycles in which the feed roller attains a peripheral speed substantially equal to the speed of the web as it is released by the treatment means and again attains the same speed as the web is engaged by the treatment means.
 2. Apparatus according to claim 1 wherein the mechanism for controllably oscillating the feed roller comprises a pivoted sector carrying an arcuate rack for driving one of the feed rollers, and a pair of angularly adjustable cams driven in synchronism with one of the treatment rolls, for actuating the sector to drive such feed roller forward aNd back once as the treatment means takes over the gripping of the web and again as such roller takes over the gripping of the web. 